To conduct a systematic review of the scientific literature and a meta-analysis of the reported risks associated with alcohol use and human immunodeficiency virus (HIV) infection in Africa.

Search Strategy

The authors searched the EMBASE and PubMed databases to identify studies conducted in Africa that related alcohol use to HIV infection. In five separate searches, they used terms relevant to a link between alcohol use and HIV infection; alcohol use and sexually transmitted infections (STIs); and alcohol use and sexually transmitted diseases. The review did not provide the precise terms used in the searches, the time-frame searched, or inclusion of studies in languages other than English. On review of titles and abstracts, the authors retained articles that 1. reported original, empirical research published in a peer-reviewed journal, and 2. considered alcohol use or drinking behavior as a potential risk factor for HIV infection. Studies of HIV risk factors, such as the presence of other STIs, high-risk sexual behavior, and sexual violence, were included in the review for the possibility that they reported rates of HIV infection among drinkers and nondrinkers.

Studies

The authors retrieved 154 citations from EMBASE and 184 citations from PubMed, from which they discerned 250 unduplicated citations. They retained 77 articles using the inclusion criteria defined above. The authors subsequently retained 20 of the 77 articles because they either reported odds ratios (ORs) comparing HIV prevalence and/or sero-conversion among drinkers and nondrinkers or included a contingency table from which ORs could be calculated. Eighteen of the 20 remaining studies were cross-sectional, measuring the relation between alcohol use and HIV prevalence in the sample, and two were prospective, examining HIV transmission among drinkers and nondrinkers. Three other studies did not report data that could be used in a meta-analysis, but did provide evidence of a positive relation between alcohol use and HIV status, risk, or transmission. These three studies were 1. an investigation of HIV prevalence and high levels of alcohol consumption among women recreation workers in Tanzania; 2. an ecological analysis relating local alcohol use with HIV prevalence rates in Tanzania; and 3. a Rwandan study that associated a woman's HIV status with her partner's alcohol use.

Participants

In the 20 studies reviewed there were 41,263 participants, of whom 15,943 were men and 25,320 were women (some of the studies were of men or of women only). All of the studies were conducted in countries of East Africa and Southern Africa. Two types of samples were encountered in the studies: representative samples from community-based surveys and samples of high-risk groups, such as bar and hotel workers, sailors, miners, beer hall patrons, pregnant women and mothers, and people seeking treatment in health facilities.

Outcome Measures

The authors were interested to see if people who drink alcoholic beverages were more likely than non-drinkers to have HIV infection. Measures of alcohol use were not consistent across studies, and drinking alcohol was indicated in any of several different ways; for example, by quantity and frequency consumed, a standardized diagnostic test of problem drinking, or the report of the participant attending bars or selling alcohol at home. The time period measured also was not uniform; some studies asked about recent drinking, for example, "in the past week," while others used an ever use/never use dichotomy. Thus, for the purposes of analysis in this review, the criterion was alcohol use (yes or no), regardless of the time period covered, and the outcome was the binary variable of HIV status (positive or negative). A second reader verified extracted data; coders were not masked to journals or authors.

Results

Univariate analysis of the association between alcohol consumption and HIV infection showed that alcohol users have significantly greater likelihood of being HIV-positive (pooled OR=1.70; 95% CI=1.45-1.99; p<0.001). The test of heterogeneity was highly significant, with a p value of <0.001, whereas publication bias was not detected (p value=0.67 and 0.12 by Begg and Mazumdar's and Egger et al.'s tests, respectively). The authors repeated the analyses using a trim and fill methodology to account for potential, but not evident, publication bias. They found that alcohol drinkers remained at relatively increased risk when compared with nondrinkers (OR=1.48; 95% CI=1.26-1.73; p<0.001). The same analysis was repeated among 11 studies that reported multivariable adjusted ORs for the association between alcohol use and HIV infection. In this analysis, the association between HIV infection and alcohol use was attenuated to OR=1.57 (95% CI=1.42-1.72; p<0.001). Heterogeneity among studies was no longer significant (p=0.60), and again publication bias was not significant (p=0.34-0.43). After applying the trim and fill methodology, the results were largely unchanged (OR=1.52; 95% CI=1.39-1.66; p<0.001).

To examine what effect study characteristics might have on the results, the authors analyzed subgroups of studies defined by participant characteristics, such as sex and whether the sample was high-risk group- or population-based. When the authors compared all studies with homogenous samples of either men (10 studies) or women (16 studies), the magnitudes of association were nearly identical, with ORs of 1.91 (95% CI=1.57-2.33) and 1.90 (95% CI=1.68-2.19), respectively. They repeated this analysis and restricted the sample to studies that reported results for both men and women. Analysis of the eight studies that fit this criterion produced pooled ORs that were more discrepant but still not meaningfully different: men, OR=1.98 (95% CI=1.76-2.22) and women, OR=1.78 (95% CI=1.53-2.08). Alcohol use was associated with significantly greater likelihood of being HIV-positive for both types of samples: population-based (OR=1.77; 95% CI=1.62-1.93) and high-risk groups (OR=2.01; 95% CI=1.56-2.58), where the latter group showed a stronger association, as anticipated (z=1.91, p<0.06). Problem drinkers were at greater risk of being HIV-positive than were drinkers who did not use alcohol symptomatically (z=2.08, p<0.04). When compared with that of nondrinkers, the pooled estimates of HIV risk were 1.57 (95% CI=1.33-1.86) for non-problem alcohol drinkers and 2.04 (95% CI=1.61-2.58) for problem drinkers.

Conclusions

The authors state that they observed evidence of a strong relation between alcohol use and HIV infection. Drinkers have a 70% increased risk of being HIV-positive when compared with nondrinkers in the bivariate analysis, and a 57% increased risk of HIV infection when potential confounders were controlled in multivariate analysis. The association remained strong and consistent after adjustment for possible publication bias, with elevated risks of alcohol use ranging from 48% to 52% for the univariate and multivariate pooled risk estimates, respectively. This conclusion is further supported by three additional findings of the analysis: 1. strong consistency and agreement exists in the estimated effect measures across studies, particularly for studies reporting a multivariate adjusted OR; 2. risk estimates are comparable across different types of samples, as for samples of men and women and for high-risk and representative populations; and 3. alcohol use demonstrates a crude dose-response relation with HIV infection such that the heaviest and most symptomatic drinkers are at greater risk of being HIV-positive than are more moderate drinkers and those who do not experience problems as a result of drinking.

Quality Rating

This systematic review meets only 20 of the 35 points in the MOOSE checklist for meta-analyses and systematic reviews of observational studies;(1) the authors state, however, that they were guided by the MOOSE checklist in the statistical analyses. The study has several limitations. First, it is difficult to assess whether the authors performed a comprehensive review of the literature, as they did not provide their search strategies and did not examine sources other than EMBASE and PubMed, including conference abstracts, author contacts, and other databases. Second, the authors note that all but two reports were cross-sectional; therefore, it is not possible to determine if a causal relation exists between alcohol use and HIV infection. An alternative, plausible conclusion is that people with HIV may drink more alcohol to cope with their life circumstances. The two prospective studies, however, showed that drinking was strongly related to increased risk of HIV infection. Third, significant heterogeneity exists in the unadjusted analysis; thus, combining the effects may not be justified. The authors note, however, that heterogeneity was not seen in the adjusted analysis and the subgroup and problem drinker analyses. Results of these analyses gave some insight into the source of the heterogeneity among the univariate ORs and suggest that the pooled estimates based on adjusted and subgroup analyses are not subject to the same caveat. Fourth, the authors mention that this analysis does not account for potential intermediate variables between alcohol use and HIV infection, such as high-risk sexual behavior, gender violence, and other STDs. In addition, the binary categorization of alcohol use limits interpretation of the results.

In Context

Several explanations may exist for the association in this review between alcohol consumption and increased risk of HIV infection (see the original article for references). In most African countries, alcohol is consumed in small bars and other informal alcohol-serving establishments patronized by high-risk men seeking new sex partners. Alcohol increases sexual risk-taking by reducing inhibitions, diminishing perception of exposure risks, increasing failure to use condoms appropriately, and increasing the frequency of sexual activity and/or number of sexual partners. Other demonstrated associations include gender violence, sexual assault, and rape. Two recent systematic reviews found that problems with alcohol consumption were associated with increased risk of STDs,(2,3) which is associated with increased risk of HIV infection. Further, a growing body of evidence implicates chronic alcohol use in compromised immune response and increased susceptibility to HIV infection.

Programmatic Implications

This systematic review and meta-analysis indicates that alcohol use is an important risk factor for HIV infection in Africa. Prevention efforts therefore should focus on people most likely to experience alcohol problems, such as frequent, heavy, and symptomatic drinking. In addition, these efforts must consider the social context in the areas where alcohol is consumed. In this regard, the authors suggest that viable alternatives could be modification and implementation of existing simple and effective methods that are graduated to an individual's increasing involvement with alcohol. These methods may include Brief Interventions developed by WHO.(4) Research and interventions also should be directed at other factors potentially linking alcohol use and HIV infection, such as high-risk sexual behavior and gender violence. Finally, efforts should be aimed directly at decreasing alcohol consumption.